Disposable carpules filled with a liquid medication are commonly used in connection with medical and dental syringe systems. In many such conventional systems, after the medication is dispensed, the injection needle remains dangerously exposed, either as part of the spent carpule or as a component attached to the syringe barrel. As a result, the used needle of a conventional injection system must typically be recapped or cautiously removed from the syringe, and handled and disposed of with extreme care. Those in the art recognize the need for a safer and more convenient medication carpule system, particularly one that is pre-filled with a selected liquid medication, includes the injection needle as an integral part of a carpule system, and in which the injection needle can be easily retracted from unsafe exposure once the medication is dispensed and prior to removal of the carpule system from the syringe.